Fog is due back in Wellington again this afternoon and is likely to force the cancellation of more flights.

A thick fog rolled in yesterday afternoon, forcing the cancellation and delay of multiple flights and disrupting Christmas holiday plans.

Air New Zealand and Jetstar both put on extra flights to clear the backlog when the airport opened this morning.

But a MetService forecaster said another wave of fog was due in Wellington about 2pm.

It would stick around till about 6am tomorrow.

It was ‘‘quite possibly’’ low enough to again force the cancellation of flights.

Air New Zealand spokeswoman Marie Hosking said the airline was still working to clear the backlog but its ability to do that could be hampered by the fog.

Elsewhere in the country, Air New Zealand reported rain was causing issues with Northland flights.

TRAVELLER CHAOS

Faced with a backlog of passengers yesterday, Air New Zealand cancelled all flights until 9 o'clock this morning and told frustrated passengers to head home and contact the helpline to rebook.

Small domestic airline Golden Bay Air shuttled its passengers to Paraparaumu. From there it flew them to the popular Tasman holiday destination.

Several Qantas and Virgin services to Australia were also cancelled yesterday.

Among those stranded at the airport were the Central Coast Mariners football team, who played the Wellington Phoenix on Saturday.

Wellington residents Alison Murray and husband Shane Wilson left Auckland on a flight home at 1.30pm, but just before their plane was due to land the pilot said the fog had rolled in earlier than expected. The plane spent almost an hour circling the region before returning to Auckland.

The pair were offered accommodation vouchers and were hoping to get on a flight today.

"I hope we get back, I have to buy food and cook Christmas dinner," Murray said.

Rebecca Reidy, 28, and James Price, 25, travelled to Wellington from Palmerston North to catch a flight to Nelson, where they were to spend Christmas with family.

Reidy said they were told by Air New Zealand staff at the check-in that they would not be able to fly until Christmas Day because there were so many stranded passengers. Price said they had managed to get on the evening ferry to Picton.

Melbourne resident Nathan Sadeghi said he arrived at Wellington Airport more than three hours before his 3.40pm flight so he could relax.

On top of the fog, Qantas had also been forced to check people in manually because of computer issues and had almost finished five hours later when the flight was cancelled, he said.

Alexandra George, who was trying to fly to Melbourne to spend Christmas with a friend, said she had spent a frustrating two hours waiting in line to check in.

"We have barely moved at all. I have a lot of connecting travel in Melbourne that I'm going to miss. It's just chaos."